Methods for the mixing of medium-viscous or more highly viscous compounds are known. In repairs of automobile body sheet, in the workshops, e.g. polyester fillers are employed for evening out unevennesses or irregularities in the sheets subsequent to the same having suffered damage in accidents or in order to carry out other sheet metal repairs.
As is well-known, these polyester fillers are manually mixed with paste-like and, in most cases, dyed hardener. In this case, the mixing is performed on a flat plate with the aid of a spatula or a wooden paddle. In the manual mixing operation with the customary quantity of 2 thru 3% of hardener compound, due to the high viscosity of the filler, additional air is automatically supplied to this pasty compound. These air bubbles are again dispersed in intensive agitation. Subsequent to the hardening of the thusly mixed filler which is then applied to the automobile body sheet, the same is once more ground over so as to even out the surface and to adapt the outline to the sheet surface. In the course of these grinding operations, small air bubbles are exposed time and time again. Said air bubbles almost always present in the fillers do represent a serious quality-related problem for an automobile paint workshop. Particularly those air bubbles which are located only a slight distance below the surface and which have not yet become visible by partial grinding, have to be designated as insidious because, after the spray painting, the vehicle is heated to 80.degree. C. with the consequence that the air inside said bubbles expands very considerably, whereby flaws on the paint surface are produced. After having cooled down, the air contracts again and may result in a further flaw or imperfection. Fillers that are mixed in the presence of a solvent are subject to the disadvantage that solvent fumes are released to which the paint shop worker is exposed and are inhaled by him.
The invention is based upon the technical problem of providing a method, with the aid of which pasty and highly viscous fillers, in particular polyester fillers in accordance with the type described in the beginning, are mechanically blended with hardener in small quantities in such a way that an air bubble-free and immediately workable filler is obtained, which, even after subsequent grinding treatment, does not result in any flaws being produced in the surfaces of the sheet metal parts to which the filler has been applied, in which process a minimum of contamination of the mixing tools is intended to take place and a complicated expensive cleaning of the mixing implements is avoided, while, furthermore, a handy device is made available to the paint shop worker, with the aid of which an automatic and mechanical mixing of fillers containing hardener, more particularly polyester fillers, with hardener is possible and this in quantities desired in each case by the paint shop worker for the requirements that occur at the particular moment.
This technical problem is solved by the method claims characterized in the claims 1 thru 3.
A first solution consists in that a predetermined quantity of the components to be intermixed, such as hardener and synthetic compound, is mixed on a moving mixing surface disposed in a closed, evacuable mixing chamber with a guide vane-like mixing member that is stationary relative to the moved mixing surface and which is vertically disposed on said surface and comprised of a rectangular or curved shaped member forming a boundary wall with an opening facing the direction of movement of the moved surface. While, due to the rolling of the approximately cylindrical or fusiform mixture composition issuing from the center of the moved mixing surface the composition is formed on the mixing disk and on the vertical boundary wall of the mixing member with the simultaneous elimination of the air bubbles present in the filler and supplied by the migration or flow process to the filler body surface by their enlargement and bursting open due to the air being evacuated from the mixing chamber by means of circulation and shifting, the rolling and thrusting motions of the mixture composition and its translatory movement being controlled with the aid of the mixing member, in this case the mixing chamber being ventilated after the termination of the mixing operation.
While this method is based on the circumstance that the moved mixing surface travels toward a stationary mixing member, a further solution consists in that a predetermined total quantity of the compound to be intermixed, such as synthetic filler and hardener, is mixed on a stationarily disposed, horizontal mixing surface in a closed, evacuable mixing chamber with a guide vane-like mixing member arranged vertically on said surface and, in relation to the stationary mixing surface, rotatingly driven about the center of the latter and which is comprised of a rectangular or curved shaped member forming a boundary wall with an opening located in the direction of rotation. By the rolling of the approximately cylindrical or fusiform mixture composition issuing or originating from the center of the mixing surface, said mixture composition is formed on the mixing surface and on the vertical boundary wall of the rotating mixing member with the simultaneous elimination of the air bubbles present in the filler and supplied by the migration or flow process to the filler body surface by their enlargement and bursting open due to the air being evacuated from the mixing chamber by means of circulation and displacement, the rolling and thrusting motions of the mixing member and its translatory movement being controlled with the aid of the mixing member, in this case the mixing chamber is ventilated after the termination of the mixing operation.
According to this method, the rotatingly driven mixing member travels toward the stationary mixing surface.
A third solution consists in that a predetermined total quantity of the components to be intermixed, such as synthetic filler and hardener, is mixed on a moving mixing surface disposed in a closed, evacuable mixing chamber with a guide vane-like mixing member arranged vertically on said mixing surface and driven counterrotatingly relative to the direction of movement of the mixing surface about the center of the latter, which is comprised of a rectangular or curved shaped member forming a boundary wall with an aperture located in the direction of rotation. While, due to the rolling of the approximately cylindrical or fusiform mixture composition issuing from the center of the mixing surface, said mixture composition is formed on the mixing surface and on the vertical boundary wall of the rotating mixing member with the simultaneous elimination of the air bubbles present in the filler and supplied by the migration or flow process to the filler body surface by their enlargement and bursting open due to the air being evacuated from the mixing chamber by means of circulation and displacement. The rolling and thrusting motions of the mixing member and its translatory movement is being controlled with the aid of the mixing member, in this case the mixture chamber is ventilated after the termination of the mixing operation.
According to this method, the rotatingly driven mixing member travels toward the stationary mixing surface.
A third solution consists in that a predetermined total quantity of the components to be intermixed, such as hardener and synthetic compound, is intermixed on a moving mixing surface disposed in a closed, evacuable mixing chamber with a guide vane-like mixing member arranged vertically on said mixing surface and driven counterrotatingly relative to the direction of movement of the mixing surface about the center of the latter, which is comprised of a rectangular or curved shaped member forming a boundary wall with an opening that faces the direction of movement of the mixing surface. While, due to the rolling of the approximately cylindrical or fusiform mixture composition issuing from the center of the mixing surface, said mixture composition is formed on the mixing surface and on the vertical boundary wall of the rotating mixing member with the simultaneous elimination of the air bubbles present in the filler and supplied by the migration or flow process to the filler body surface by their enlargement, bursting open due to the air being evacuated from the mixing chamber by means of circulation and displacement. The rolling and thrusting motions of the mixing member and its translatory movement is controlled with the aid of the mixing member, in this case, the mixing chamber is ventilated after the termination of the mixing operation.
According to this method, the moving mixing surface is made to travel contrary to the mixing member, which likewise rotates contrary to the direction of movement of the mixing surface.
In those cases where the mixing surface is moved contrary to the mixing member, the mixing surface is constructed in the form of a horizontal mixing disk driven rotatingly about its center shaft.
In addition, the technical problem is solved by three differently constructed devices, in which connection the device for the method in which the mixing surface travels contrary to the mixing member, is constructed in such a way that it is comprised of a mixing container having a square or circular cross-section, of a bottom portion, of a circumferential side wall and of a cover portion which seals the upper container opening. The cover portion is secured to the container side wall with the aid of mechanical means or by means of a vacuum in the operative state of the device, of a horizontal mixing disk disposed in the mixing chamber of the mixing container. The mixing disk supported on the bottom portion and rotatingly driven about its vertical center axis with the aid of a driving means arranged on the bottom portion and of a mixing member stationarily disposed above the mixing disk opposite the same. The mixing member is constructed in the form of a shaped member disposed in the mixing chamber vertical relative to the mixing disk in the form of a rectangular or curved boundary wall having the function of a mixing vane and with an opening facing the direction of rotation of the mixing disk, the mixing disk is detachably connected to the drive shaft of the driving means and the mixing container being provided with a connecting piece disposed in the container wall which communicates with a vacuum generating unit.
The device for performing the method, according to which the mixing member is moved rotatingly toward the stationary mixing surface, is comprised of a mixing container having a square or circular cross-section, of a bottom portion, of a circumferential side wall and of a cover portion closing the upper container opening which, with the aid of mechanical means or by means of a vacuum, is secured to the container side wall in the operative state of the device, of a horizontal mixing disk disposed in the mixing chamber of the mixing container. The mixing disk is detachably supported on the bottom portion, and of a mixing member disposed above the stationary disk opposite the same and rotatingly driven about a vertical shaft with the aid of a driving means, said mixing member being constructed in the form of a shaped member disposed in the mixing chamber vertically relative to the mixing disk in the form of a rectangular or curved boundary wall having the function of a mixing vane and with an opening facing the mixing disk, in which the mixing container is provided with a connection piece disposed in the container wall which is connected to a vacuum generating unit.
For the method in which both the mixing surface as well as the mixing member are moved toward each other, a device is provided that is comprised of a mixing container having a square or circular cross-section, of a bottom portion, of a circumferential side wall and of a cover portion closing the upper container aperture which, with the aid of mechanical means or by means of a vacuum, is secured to the container side wall in the operative state of the device, of a horizontal mixing disk disposed in the mixing chamber of the mixing container, said mixing disk being supported on the bottom portion, it being rotatingly driven about its vertical center shaft with the aid of a driving means mounted on the bottom portion, and of a mixing member disposed above the rotatingly driven mixing disk opposite the same about a vertical shaft with the aid of a drive means, and of a mixing member above the rotatingly driven mixing disk which, in relation to the latter, is, with the aid of a driving means, counterrrotatingly driven relative to the direction of rotation of the mixing disk about a vertical shaft, said mixing member being constructed in the form of a shaped member disposed in the mixing chamber vertically relative to the mixing disk in the form of a rectangular or curved boundary wall having the function of a mixing vane and with an opening facing the direction of rotation of the mixing disk, in which the mixing disk is detachably coupled to the drive shaft of the driving means, while the mixing container is provided with a connecting piece that communicates with a vacuum generating unit.
With this method and the device designed for its performance, an automatic mechanical intermixing of fillers and hardeners, particularly in the quantities required in each case by the paint shop worker, which may be small or large and which depend in each case on the size of the areas to which filler is to be applied, in which connection larger areas are treated section-wise, is possible. Moreover, the filler produced is workable immediately. A refilling onto a working plate is dispensed with since the mixing plate of the mixing device with the filler mixed thereupon can be removed and brought within the area of the surfaces on which it is to be applied. The automatic mixing is thus effected in a closed mixing chamber which is evacuated during the mixing operation. In the course of this mixing operation, it is evacuated by approximately 90% to 100 mb by means of a vacuum pump. If necessary, solvent fumes produced during the mixing operation are drawn off along with the air at the same time so that the paint shop worker is not exposed to solvent fumes. A consequence of this is that the air pockets present in the mixing compound, viz. air bubbles, are enlarged to the ninefold of their volume and, during the mixing operation, moved to the surface of the mixture composition. Due to their size, burst on the surface of the mixture composition, i.e. the filler. Owing to the circumstance that the mixing of the components, one of which is a hardener, is effected in a vacuum and on a mixing disk in connection with a specially designed mixing member. Meanwhile the mixture body, due to the motion cycles of the mixing disk and/or the mixing member, besides a rotating motion, also executes a transversal movement, the filler is rendered free of air bubbles during the mixing operation. In this connection, the mixing operation is planned in such way that the intermixing can preferably be performed within 15 to 50 seconds. The thusly obtained air bubble-free filler is then applied to the automobile body sheet surface by means of a spatula. The filler is gelled (hardened) after 4 to 5 minutes so that the grinding operation can be carried out after a further 15 minutes. The grinding operations performed now no longer show any air bubble inclusions so that, with this method and the devices and means constructed for them, a significant quality enhancement in the automobile body repair and painting trade is achieved.
This movement of the air bubbles toward the surface of the mixture composition is, apart from the evacuation of the mixing chamber, accomplished by the rolling and shifting movement of the filler. By means of the movement of the composition achieved in this case, the air bubbles are displaced to the surface. Also small air bubbles with lacking buoyant force are conveyed to the surface. Owing to the various kinetic cycles of the mixing disk and the mixing member, a complete and thorough intermixing of the filler components is achieved within a minimum of space since, due to the vane-like construction of the mixing member with a lateral reception space for the mixed product, product laterally, is limited only by the vertical boundary wall of the mixing member and, at the bottom, by the mixing disk, the filler components stay on a spot on the mixing disk that is predetermined by the position of the mixing member during the mixing operation and this spot on the mixing disk can be changed uniquely by altering the position of the mixing member, an optimal thorough blending is ensured at all times. The intensive intermixing of the filler components is also additionally achieved by a constant change of the shape of the mixture composition due to the circumstance that the setting angle of the mixing member relative to the mixing disk is changed. By an alternate reciprocal swiveling of the mixing member the mixture composition assumes a continually changing shape during the mixing operation. This perpetual changing of the configuration of the mixture composition, together with the rolling motions of the mixture composition between the mixing disk and the mixing member contributes to the filler components being vigorously intermixed so that, in connection with the evacuation of the mixing chamber, even if highly viscous compounds are involved, a movement of the air bubbles from the interior of the compound to its surface is brought about. The swivel motions of the mixing member are in this case executed only within a small area. This area is adjusted in such a way that, during the mixing operation, no mixing compound is able to migrate from the area of the mixing disk. The mixing member may be swiveled manually, electromotively or electromagnetically. The central point of the mixture composition is subject to a constant movement since, in dependence of the movement of the mixing member, it moves constantly, as a result of which the hardener travels through the entire filler.
Furthermore, only those parts of the mixing device that come into direct contact with the filler are contaminated by the same and, since only a few parts, viz. mixing member and mixing disk, do come into contact with the filler. A cleaning of said parts subsequent to the termination of the mixing operation is easy and in no way expensive. If the mixing disk and the mixing member are fabricated from a highly polished plastic, such as polyethylene, polyurethane or tetrafluorocarbon, in that case a removal of remainders of gelled filler is readily effected.
Besides fillers which contain solvents, it is also possible to mix fillers that are solvent-free with equally satisfactory results, particularly when dyeing has to be carried out. Apart from silicon rubber, polyurethane fillers, epoxide fillers, fillers and putties, all components, and this in the smallest quantities, can be intermixed. For the paint shop worker, the mixing disk itself forms the transporting means for the finished filler.
Once the mixing operation is terminated, the mixing chamber ventilated and the mixing container opened, then the mixing disk or the mixing plate lying on the mixing disk is removed from the mixing chamber and the mixing product obtained (filler) is applied directly to the surface to be treated, e.g. the automobile body sheet surface, on which the filler then gels (hardens).